Discovery of Eight z ~ 6 Quasars in the Sloan Digital Sky Survey Overlap Regions

We present the discovery of eight quasars at z~6 identified in the Sloan Digital Sky Survey (SDSS) overlap regions. Individual SDSS imaging runs have some overlap with each other, leading to repeat observations over an area spanning >4000 deg^2 (more than 1/4 of the total footprint). These overlap regions provide a unique dataset that allows us to select high-redshift quasars more than 0.5 mag fainter in the z band than those found with the SDSS single-epoch data. Our quasar candidates were first selected as i-band dropout objects in the SDSS imaging database. We then carried out a series of follow-up observations in the optical and near-IR to improve photometry, remove contaminants, and identify quasars. The eight quasars reported here were discovered in a pilot study utilizing the overlap regions at high galactic latitude (|b|>30 deg). These quasars span a redshift range of 5.86<z<6.06 and a flux range of 19.3<z_AB<20.6 mag. Five of them are fainter than z_AB=20 mag, the typical magnitude limit of z~6 quasars used for the SDSS single-epoch images. In addition, we recover eight previously known quasars at z~6 that are located in the overlap regions. These results validate our procedure for selecting quasar candidates from the overlap regions and confirming them with follow-up observations, and provide guidance to a future systematic survey over all SDSS imaging regions with repeat observations.Comment: AJ in press (8 pages

Temporal correlation analysis between malaria and meteorological factors in Motuo County, Tibet

<p>Abstract</p> <p>Background</p> <p>Malaria has been endemic in Linzhi Prefecture in the Tibet Autonomous Region (TAR) over the past 20 years, especially in Motou County with a highest incidence in the country in recent years. Meteorological factors, such as rainfall, temperature and relative humidity in Motou County were unique compared to other areas in Tibet as well as other parts of China, thus the objective of this work was to analyse the temporal correlation between malaria incidence and meteorological factors in Motou County, in order to seek the particular interventions for malaria control.</p> <p>Methods</p> <p>The meteorological and malaria data during 1986-2009 in Motuo County were studied to analyse the statistical relationship between meteorological data time series and malaria incidence data series. Temporal correlation between malaria incidence and meteorological factors were analyzed using several statistical methods. Spearman correlation analysis was conducted to examine the association between monthly malaria incidence and meteorological variables. Cross-correlation analysis of monthly malaria incidence series and monthly meteorological data time series revealed the time lag(s) of meteorological factors preceding malaria at which the series showed strongest correlation. Multiplicative seasonal auto-regressive integrated moving average (SARIMA) models were used in the cross-correlation analysis with pre-whitening which remove seasonality and auto-correlation of meteorological data series. Differenced data analysis which called inter-annual analysis was carried out to find underlying relationship between malaria data series and meteorological data series.</p> <p>Results</p> <p>It has been revealed that meteorological variables, such as temperature, relative humidity and rainfall were the important environmental factors in the transmission of malaria. Spearman correlation analysis demonstrated relative humidity was greatest relative to malaria incidence and the correlation coefficient was 0.543(<it>P </it>< 0.01). Strong positive correlations were found for malaria incidence time series lagging one to three months behind rainfall (<it>r </it>> 0.4) and lagging zero to two months behind temperature and relative humidity (<it>r </it>> 0.5) by the cross-correlation. Correlations were weaker with pre-whitening than without. The cross-correlograms between malaria incidence and various meteorological variables were entirely different. It was fluctuated randomly for temperature but with trend for the other two factors, which showed positive correlated to malaria when lag was from 0 to 5 months and negative from 6 to 12 months. Besides, the inter-annual analysis showed strong correlation between differenced annual malaria incidence and differenced meteorological variables (annual average maximum temperature, annual average relative humidity and annual average rainfall). The correlations coefficients were -0.668 (<it>P </it>< 0.01), 0.451(<it>P </it>< 0.05) and 0.432(<it>P </it>< 0.05), respectively.</p> <p>Conclusion</p> <p>Meteorological variables play important environmental roles in malaria transmission in Motou County. Relative humidity was the greatest influence factors, which affected the mosquito survival directly. The relationship between malaria incidence and rainfall was complex and it was not directly and linearly. The lags of temperature and relative humidity were similar and smaller than that of rainfall. Since the lags of meteorological variables affecting malaria transmission were short, it was difficult to do accurate long-term malaria incidence prediction using meteorological variables.</p

Vision-based Deformation Measurement for Pile-soil Testing

Image measurement technology has been widely used in monitoring the deformation of the soil field around the pile with its advantages of no damage, no contact, full-field measurement, no added quality and high sensitivity. But there are few researches on image-based bearing deformation measurement of the pile. Through an indoor pile-soil semi-model test, the rigid body displacement and load-bearing deformation of a new type of prefabricated steel tube pile foundation under horizontal load was measured based on image features. In this study, the concept of optical extensometer is first applied to the measurement of local average strain of a non-uniform deformed structure. Based on an improved feature point tracking algorithm SURF-BRISK, non-contact measurement of tiny strain of pile body is realized. In addition, based on DIC technology, this study also obtained the progressive development of displacement field of soil around pile. The above work fully reflects the non-contact convenience and full-field richness of the optical measurement method compared with the traditional measurement method

Research on Uplift Bearing Performance of Assembled Steel Pipe Pile used in Transmission Lines in Mountainous Terrain

Assembled steel pipe pile, which is a novel pile foundation, is developed in the paper. The ultimate uplift bearing capacity of the pile is proposed, and simulation by Plaxis3D and the corresponding experiment are performed to verify the theory. In the simulation, ultimate uplift bearing capacity of the assembled steel pipe pile and ultimate lateral frictional resistance of the interface of pile-soil increases with the increasing of the strength and stiffness of the interface of pile-soil, and with the increasing of length-diameter ratio, ultimate uplift bearing capacity of the assembled steel pipe pile increases while the ultimate lateral frictional resistance decreases gradually. The ultimate lateral friction is influenced by both of the strength of the soil around the pile and the interface of pile-soil, and the ultimate uplift bearing capacity obtained by simulation and theoretical calculation are close. Long-gauge FBG sensors are used in the experiment for measuring the longitudinal strain of the pile, and the error of ultimate uplift bearing capacity between the results of experiment and theory is less than 10%

Project Overview of the Beijing-Arizona Sky Survey

The Beijing-Arizona Sky Survey (BASS) is a wide-field two-band photometric survey of the Northern Galactic Cap using the 90Prime imager on the 2.3 m Bok telescope at Kitt Peak. It is a four-year collaboration between the National Astronomical Observatory of China and Steward Observatory, the University of Arizona, serving as one of the three imaging surveys to provide photometric input catalogs for target selection of the Dark Energy Spectroscopic Instrument (DESI) project. BASS will take up to 240 dark/grey nights to cover an area of about 5400 deg$^2$ in the $g$ and $r$ bands. The 5$\sigma$ limiting AB magnitudes for point sources in the two bands, corrected for the Galactic extinction, are 24.0 and 23.4 mag, respectively. BASS, together with other DESI imaging surveys, will provide unique science opportunities that cover a wide range of topics in both Galactic and extragalactic astronomy.Comment: 10 pages, submitted to PAS

Maternal Dietary Diversity and Small for Gestational Age:The Effect Modification by Pre-Pregnancy Body Mass Index and Gestational Weight Gain in a Prospective Study within Rural Sichuan, China (2021–2022)

Infants born small for gestational age (SGA) remains a significant global public health concern, with potential interconnections among maternal diet, pre-pregnancy BMI, gestational weight gain (GWG), and SGA. This prospective study investigated the association between dietary diversity (DD) during pregnancy and the risk of SGA, as well as the synergistic effect of DD with pre-pregnancy BMI and GWG on SGA. Maternal dietary intake during pregnancy was assessed using 24 h dietary recalls, and dietary diversity scores (DDS) were calculated based on the FAO’s Minimum Dietary Diversity for Women index. Infant information was followed up. The Poisson regression model was employed to determine the association between maternal DD and SGA. Interactions between DD and pre-pregnancy BMI or GWG were evaluated under additive and multiplicative models. Among the 560 singleton live births, 62 (11.07%) were classified as SGA. After adjusting for potential confounders, the DDS exhibited a protective effect against SGA (aRR: 0.76; 95% CI: 0.62–0.95). DD modified the association between being underweight prior to pregnancy and SGA on the additive scale (interaction contrast ratio = 7.39; 95% CI: 5.84, 8.94). These findings suggest that improving dietary diversity during pregnancy, particularly among women with a low pre-pregnancy BMI, may be a feasible strategy to reduce the risk of SGA newborns.</p

Fast Fourier transport analysis of surface structures fabricated by laser interference lithography

This paper presents an FFT (fast Fourier transform) analytical method for the study of surface structures fabricated by laser interference lithography (LIL). In the work, the FFT analytical method combined with Gaussian fitting is used to determine the periods and pattern distributions of surface structures from frequency spectra. For LIL, the processing parameters of incident and azimuth angles can be obtained corresponding to the period and pattern distribution. This work facilitates the detection of micro- and nano-structures, the analysis of pattern distribution in engineering, and the processing error analysis of LIL

Spectral Energy Distributions and Age Estimates of 172 Globular Clusters in M31

In this paper we present CCD multicolor photometry for 172 globular clusters (GCs), taken from the Bologna catalog (Battistini et al. 1987), in the nearby spiral galaxy M31. The observations were carried out by using the National Astronomical Observatories 60/90 cm Schmidt Telescope in 13 intermediate-band filters, which covered a range of wavelength from 3800 to 10000A. This provides a multicolor map of M31 in pixels of 1.7"*1.7". By aperture photometry, we obtain the spectral energy distributions (SEDs) for these GCs. Using the relationship between the BATC intermediate-band system used for the observations and the UBVRI broad-band system, the magnitudes in the B and V bands are derived. The computed V and B-V are in agreement with the values given by Battistini et al. (1987) and Barmby et al. (2000). Finally, by comparing the photometry of each GC with theoretical stellar population synthesis models, we estimate ages of the sample GCs for different metallicities. The results show that nearly all our sample GCs have ages more than 10^{9} years, and most of them are around 10^{10} years old. Also, we find that GCs fitted by the metal-poor model are generally older than ones fitted by the metal-rich model.Comment: 38 pages, 7 figures will appear in the February 2003 issue of A